Thermal degradation of aqueous DEEA solution at stripper conditions for post-combustion CO2 capture

• The thermal degradation of DEEA was experimentally investigated in a 600 mL stainless steel autoclave.
• The thermal degradation of DEEA was very sensitive to the operational parameters within the range presented in this work.
• The thermal degradation rate of DEEA was lower than that of MEA for the same condition.

Reliable estimation of amine degradation, which can lead to significant problems such as solvent losses, byproducts, fouling, foaming, corrosion, and increase in viscosity, is very important for developing effective and efficient amine solvents with high chemical and thermal stability. In this study, thermal degradation of aqueous N,N-diethylethanolamine (DEEA) solution was investigated as a function of temperature, CO2 loading, and DEEA concentration in a 600 mL stainless steel autoclave. The results show that DEEA thermal degradation without CO2 was quite low and was effectively negligible. Also, DEEA solution demonstrated more resistance towards thermal degradation with CO2 than MEA. Furthermore the results of the effects of degradation on the equilibrium solubility of CO2 in aqueous DEEA solution indicates that some of the degradation products also have the ability to absorb CO2 resulting in less DEEA make-up to achieve the initial DEEA concentration equilibrium CO2 absorption capacity. A possible mechanism for DEEA thermal degradation has been developed to explain the occurrence of major products generated during the degradation process. In addition, a kinetic model has been established to predict the rate of the thermal degradation of DEEA. The model had an absolute average deviation (AAD) of 3.7% between the experimental rate and the predicted rate.